National Institute for Environmental Studies Invasive Species of Japan Japanese | English
  1. Invasive Species of Japan >
  2. Invertebrates (except insects) >
  3. Crangonyx floridanus

Crangonyx floridanus

Basic information
Scientific name Crangonyx floridanus (No picture)
Common names Florida crangonyctid, freshwater amphipod
Higher taxon Crangonyctidae, Gammaridea, Amphipoda, Malacostraca, Arthropoda
Natural range Southwestern USA.
Habitat Various freshwater, lotic or lentic habitats with sand graval or mud bottom with or without aquatic plants.
Invasion information
Range in Japan Hokkaido, Akita, Yamagata, Miyagi, Fukushima, Shizuoka, Aichi, Gifu, Toyama, Ehime, Oita Prefs., all the prefectures in Kanto, Koshin-etsu, and Kinki District, and Fukuejima Is. (Goto Islands). There have been many records especially in Tokyo and Kangawa. In some regions such as Shizuoka Pref., this species have spread gradually. Range in Japan
Date The first record in Japan was in 1989, in a small river in Abiko, Chiba Pref. to Toride, Ibaraki Pref.
Route Waterweed accompanied with this species was possibly dumped into water area. Within USA, this species have spread by hitchhiking on ballast water and some fishery materials.
Impact Potentially: Competition. This species sometimes co-occur with native amphipods.
Actually: Damage on agriculture of Japanese horseradish in Shizuoka Pref.
Native organism(s) affected: Competition with Jesogammarus. (Annanogammarus) naritai in Shiga Prefs. Co-occurrence with J. spinopalpus in Chiba and Saitama Prefs., and J. jesoensis in Nagano Pref. have been observed.
Regulation in Japan Releasing is prohibited, and keeping needs permissions in Shiga Pref. by the ordinance.
Introduced range in other countries
Reference Notes
  • Kanada et al. (2007) Distribution of an alien species, Crangonyx floridanus Bousfield (Crustacea: Amphipoda: Crangonyctidae) in Japan. Jpn J Limnology. 68(3), 449-460 (in Jpn with Englis abst)
  • Nagakubo et al. (2011) Rapid expansion of the distributional range and the population genetic structure of the freshwater amphipod Crangonyx floridanus in Japan. Limnology, 12(1), 75-82.
  • Tomikawa (2012) An annoted inventory with a key to freshwater Amphipoda (Crustacea) from Japan. TAXA, Proc Jpn Soc Syst Zool. 32, 39-51 (in Jpn with English abst)
  • etc.